I used to work at Yodlee and do some Yodlee consulting on the side. I can't speak to the license fees, but to the folks that say "build your own", I don't really recommend that.
Not sure what kind of site you are trying to build, but aggregation is a really Long Tail kind of functionality. I've heard countless times from people that "Yodlee supports 15 of my institutions but they don't support my one bank and that makes the aggregated data useless without it." And Yodlee supports thousands of sites. Even if you built custom support for 80% of the sites, the "all or nothing" mentality of a lot of aggregation users means that does not translate to satisfying 80% of the users.
Not sure what kind of site you are trying to build, but aggregation is a really Long Tail kind of functionality. I've heard countless times from people that "Yodlee supports 15 of my institutions but they don't support my one bank and that makes the aggregated data useless without it." And Yodlee supports thousands of sites. Even if you built custom support for 80% of the sites, the "all or nothing" mentality of a lot of aggregation users means that does not translate to satisfying 80% of the users.